Carburetor



Aug. 27, 1940. V-E.. o. wlRTH 2,212,926-

CARBURET'QR Y Filed sept. 4, `1956` s sheets-sheet 1 ATroRNEY.

Patented Aug. 27, 1940 UNITED STATES 2,212,926 cAmsUREToit Emil 0.Wirth, South Bend, Ind., assignor, by4

mesne assignments, to Bendix Aviation Corporation, South Bend, Ind., acorporation of Delaware 'Application September 4, 1936, Serial No.99,449

9 Claims.

This invention relates to carburetors, and has for its object to improvethe operating characteristics of carburetors, more particularly thoseused on automotive vehicles.

A further object of the invention is to provide a fuel reservoir ofimproved construction, which will minimize surging due to tilting and toacceleration, whether positive or negative acceleration, or accelerationtoward the center of a circle, as l occurs when the vehicle to which thecarburetor is attached is turning a corner.

Another object of the invention is to provide a carburetor which willhave increased eiiiciency and economy of fuel, and which may be built atl minimum cost.

Further objects and advantages of the invention will be apparent fromthe following description, taken in connection with the appendeddrawings, in which:

Figure 1 is a side elevation of a carburetor embodying the invention;

Figure 2 is a vertical section taken on the line 2-2 of Figure l;

Figure 3 is a horizontal section taken on the line `3-3 of Figure 1;

Figure 4 is a fragmentary section taken on the line 4-4 of Figure 3;

Figure 5 is a section taken on the line 5-5 of Figure 3;

Figure 6 is a section taken on the line 6--6 ofl Figure 3;

Figure 'l is a fragmentary section taken on the line 1-1 of Figure 3;and

Figure 8 is a fragmentary section taken on the line 8-8 of Figure 3.

Referring more particularly to the drawings, the carburetor disclosedtherein is of the downdraft, double-barrel type, although the inventionmay be applied to other types of carburetors. It includes an air hornsection I0 and a main body section l2, both preferably formed bydie-casting; and a throttle body section I4, preferably formed bysand-casting, designed to be connected to the intake manifold I6 butseparated therefrom by a heat-insulating gasket I8.

Section I0 forms an air inlet 20 which is controlled by a choke valve 22of any suitable construction, manipulated either manually or auto#matically in the known manner. Below choke valve 22, the walls of theinduction passage are ared as indicated at 23 and the passage thenbranches into two mixture passages 24 controlled by throttle valves 26mounted on a common shaft 21 and controlled by means hereinafterdescribed. au Each passage 24 comprises a smaller .venturi 28 suppliedwith fuel from a fuel nozzle 30 and discharging into a larger venturi32. 'Ihe construction and arrangement of the fuel nozzles is shown inFigure 4, and may be similar to that shown in the copending applicationof Frank C. Mock, S. N. 98,680, filed AugustSl, 1936. As illustrated,each nozzle is provided with a calibrated fuel metering restriction 35positioned in a threaded plug 36 which projects from a boss 31 formedintegral with the main'body section l2. The nozzle is also provided withan air-bleeding and gas-separating chamber 38, all as more fullydescribed in said Mock' application.

Fuel is supplied to the main nozzles at constant head by means of aconstant-level fuel reservoir which extends entirely around the venturis32 and includes float compartments 40 and 4| interconnected by a passage42, and chambers 44 and 46, separated from the float compartments bybaflies 48 and 50 which terminate short of the wall 23 to providerestricted passageways 52 leading to the float compartments 40 and 4 I.

An acceleration pump is incorporated in *he carburetor, and comprises apiston 53 having a piston rod 54 and slidable in a cylinder 55 which isformed integral with a partition wall 56 which completely obstructscommunication between chambers 44 and 46. The acceleration pumpdischarges through a pressure actuated outlet valve 51 of knownconstruction, which also serves as an economizer valve. 'I'he valve 51connects with discharge tubes 58 leading into the venturis 28. Acylindrical recess 59 in chamber 46 is designed to receive avacuum-actuated economizer valve (not shown) in cases where it is deemedadvisable to incorporate this type of economizer in the carburetor. Theinlet of the pump is formed by a cross passage 60 which communicateswith both of chambers 44 and 46 and, as shown in Figure 7, leads to awell 6I which leads through a check valve 62 to the cylinder 55.

Removablev plugs 63 at the bases of chambers 44 and 46 permit insertionand removal of the nozzles 30 and form fuel wells 64 of small capacityat the lowermost portions of chambers 44 and 46.

Idling fuel for each mixture passage 24 is drawn from the nozzle 30through a lateral passage 65, thence upwardly through an idling tube 66to a point above the normal fuel level in the carburetor (indicated bythe line L-L in Figure 2), and thence downwardly through a passage 61 toan idling nozzle 68, of known construction, discharging adjacent thethrottle 26. Air is bled into the idling fuel through a passage leadingfrom the air inlet of the carburetor to a calibrated member ||2 which ismounted below the carorifice 12 positioned above the normal fuel level.The upper portions of passages 61 are formed in a pair of bosses 14,integral with bales 48 and 50, respectively.

Floats 16 are mounted in compartments 40 and 4| andare rigidly connectedto each other by a member 18 having a lever 80 formed integral therewithand rotatably engaging a pin 82 carried by a bracket 84 depending fromthe air horn section |0. A valve cage 86 also depends from section |0,and houses a needle valve 88 which is secured, as by a wire 90, to thelever 80, so that in case the valve sticks to its seat the weight of theiloats will draw it therefrom. Wire 90 permits a limited amount oflateral movement of valve 88, and cage 86 limits such movement. A stop9| formed on lever 80 limits the downward movement of the oats bycontacting the cage 86. The float valve mechanism just described ismounted in a bay 92`of the fuel reservoir, and controls the inflow offuel through inlet 94 to maintain the fuel in the reservoir at aconstant level.

The throttle control mechanism is best shown in Figure 1, and comprisesa lever 96 fixed to throttle shaft 21 and connected through anoverrunning connection to a rod 98 which is actuated by the acceleratorpedal in the known manner. 'Ihe usual return spring is indicateddiagrammatically at |00. An arm |02 of the lever 96 is connected throughrod |04 and pivoted lever |06 to the piston rod 54 of the accelerationpump. Another arm |08 of the lever 96 is provided with a stop screw ||0designed to contact a rotatable buretor and controlled by a coiledspring thermostat |I4, so that when the engine is cold the member ||2will be rotated so as to bring one of a series of stops ||6 intojuxtaposition with screw ||0 to thereby prevent the throttle valves fromreturning to their fully closed position, thereby increasing the idlingspeed of the engine when it is cold. A stop ||l8 on the carburetor isdesigned to contact with an ear |20 formed on lever 96 to limit themovement of the throttles in the opposite or opening direction.

The operation of the carburetor will in general be clear from theforegoing description. Assume that the vehicle to which the carburetoris attached undergoes positive acceleration in the direction indicatedby the arrow in Figure 3, which may be the normal direction of movementof the vehicle, although the carburetor may be mounted in the reversedirection if desired. Inertia will tend to cause the fuel in thereservoir to flow into the passage 42 and thus uncover the plugs 36 andcause the engine to misre or stall. This tendency, however, is resistedby the restrictions 52, which permit only a slow flow of fuel out of thecompartments 44, 46. The head of fuel at the plugs 36 will be decreasedsome- What, but the inertia effect on the columns of fuel within thenozzles 30 will tend to compensate for this effect, so that the supplyof fuel issuing from the main nozzles will be maintained at or aboutnormal. Another factor opposing this tendency is the relatively smallcapacity of passage 42, which, under the conditions mentioned, causesthe fuel level therein to quickly rise to a point where a condition ofdynamic equilibrium is quickly reached between the fuel level in thepassage and that at other points in the oat chamber.

Conversely, when the acceleration of the vehicle in the direction of thearrow in Figure 3 is negative, as when the brakes are applied to anautomobile, the fuel will tend to flow from the float compartments 40,4| to the chambers 44, 46, but restrictions 52 will permit only a slowflow thereto; the level of fuel at the plugs 36 will be increasedsomewhat, but this will be compensated by the inertia of the columns ofliquid "in nozzles 30.

When the carburetor is subjected to an acceleration transverse to thoseabove discussed, as when the automobile to which it is attached isturning a corner, the fuel will tend to flow from one of floatcompartments 40, 4| to the other. Such ow, of itself, does no harm,since the floats 16, being rigidly connected together, will properlycontrol the opening and closing of the needle valve 88 under suchconditions. However, it is important that such flow from one floatcompartment to the other does not drain the chamber, 44 or 46, which ison the side toward which the carburetor is being accelerated, nor floodthe other chamber by forcing excess fuel thereinto. Assuming that thecarburetor is being accelerated upwardly as viewed in Figure 3, it willbe noted that excessively rapid surging of the fuel from floatcompartment 40 to the other compartment 4| is prevented by therelatively narrow width of passage 42, while partition 56 prevents flowon the opposite side altogether. Some of the fuel from the compartment40 will drain into chamber 44, thereby preventing exposure of its plug36. Some of the fuel from chamber 46 may drain into the compartment 4|;in both cases the ow will be relatively slow, rather than a rapid surge.If this condition is maintained overa considerable period, as whendriving at high speed over a small circular track or when driving forsome distance on a laterally inclined roadway, the compartment 4| willbe come almost completely filled with fuel and the compartment 40 almostcompletely empty. Unless the conditions are extreme, however, there willbe maintained ln the compartment 40 a suiciently high fuel level toprovide a continuous flow from the inlet 94 through said compartment andrestriction 52 to chamber 44, to replenish the supply discharged throughthe nozzle. Likewise, there will be a continuous flow of fuel from inlet94 through the compartment 4| and restriction 52 to chamber 46, toreplenish the supply discharged by its nozzle; in this latter case, theflow of fuel from the compartment 4| through restriction 52, against theaccelerative or gravity force, is assisted by the high level of fuel inthe float compartment 4|, assuming that suilcient time has elapsed topermit the conditions tol become stabilized.

In cases where the carburetor, instead of being accelerated, is tiltedin any direction, the operation is substantially the same as in thecases of acceleration just described.

Although the invention has been described with reference to a specificembodiment thereof, it is not limited to that embodiment, nor otherwiseexcept by the terms of the appended claims.

I claim:

1. In an automotive vehicle, a carburetor comprising a verticalinduction passage of elongated cross-section having its shorterdimension extending in the normal direction of movement of the vehicle,a fuel reservoir extending substantially around said induction passageand comprising a pair of fuel compartments of relatively large capacitypositioned laterally of the induction passage, level-controlling membersin said compartments, a passage of relatively small capacity connectingsaid compartments, baflies forming a pair of fuel chambers separatedfrom each other by a partition and from the remainder of the reservoirby restricted passages, and nozzles connecting the chambers with theinduction passage.

2. The invention defined in claim 1, wherein the inlets of said nozzlesare disposed relative to the induction passage in the direction ofnormal movement of the vehicle to which the carburetor is attached.

3. The invention defined in claim 1, wherein each of the fuel chamberscomprises a well of small capacity at the lower-most point thereof, andthe nozzles extend into said wells.

4. In a carburetor for an automotive vehicle, an annular fuel reservoir,an induction passage extending vertically through the fuel reservoir,said reservoir comprising a pair of fuel wells separated from each otherby a partition extending across one side of the reservoir andcommunicating with the remainder of the reservoir by restrictedpassages, and inclined fuel nozzles leading' from the fuel wells to theinduction passage.

5. In a carburetor, an annular constant level fuel reservoir, a pair ofinduction passages extending vertically through the fuel reservoir, saidreservoir including a pair of vertically extending fuel wells ofrelatively small capacity and crosssectional area compared to that ofthe entire reservoir, each of said wells having restricted communicationwith the remainder of the reservoir whereby the fuel level therein willnot be materially changed upon sudden acceleration of the carburetor ina substantially horizontal plane, and a pair of main fuel nozzles havingmetering restrictions therein extending from the Wells to the inductionpassages, said fuel wells being positioned in the forward portion of thefuel reservoir and the reservoir opposite said fuel wells consisting ofa` narrow passage of relatively low capacity.

6. In a carburetor for an automotive vehicle; a vertical inductionpassage of elongated crosssection having its shorter dimension extendingin the normal direction of movement of the vehicle; an annular fuelreservoir surrounding said induction passage comprising a pair of fuelcompartments of relatively large capacity positioned at opposite sidesof the induction passage, a passage of relatively small capacityconnecting the fuel compartments, and a pair of fuel chambers ofrelatively small capacity separated from each other by a partitionextending across one side of the reservoir and communicating with! theremainder of the reservoir by restricted passages whereby the fuel levelin said chambers will not be materially changed upon sudden accelerationof the carburetor in a substantially horizontal plane; a fuel inlet tosaid reservoir; a pair of interconnected floats in said compartmentscontrolling said inlet; and main fuel nozzles connecting the chamberswith the induction passage.

'1. In a carburetor, an annular fuel reservoir, a downdraft inductionpassage extending through said reservoir, a fuel inlet to saidreservoir, interconnected floats positioned at opposite sides of thereservoir controlling the inlet, a main fuel nozzle having an inlet inthe forward portion of said reservoir and discharging into the inductionpassage, and vertically extending wall structure forming a partition insaid reservoir and partially surrounding said fuel nozzle inlet to forma chamber of limited capacity and small cross-sectional area havingrestricted communication with the remainder of the fuel reservoir.

8. The invention defined in claim 7 wherein the reservoir opposite saidchamber comprises a narrow passage of limited capacity to prevent rapidflow of fuel from the vicinity of one oat to the vicinity of the otheroat.

9. In' a carburetor for an automotive vehicle, a constant level annularfuel reservoir, a vertical induction passage extending through saidreservoir, a main fuel nozzle connecting said reservoir with theinduction passage and having a metering restriction therein, a wallpartially surrounding the inlet to said nozzle for forming a verticallyextending fuel well of limited capacity and cross-sectional area, saidwell having restricted communication with the remainder of saidreservoir whereby the effective fuel level at said inlet will not bematerially changed upon sudden acceleration of the carburetor in asubstantially horizontal plane, fuel inlet to said reservoir at a pointspaced fromgsaid fuel well, a valve in said inlet, and meansresponsive-tothe level of the fuel in the reservoir for controlling saidvalve.

EMIL 0. WIRTH.

